Bug #5626: Incorrect inference regarding static context item type in xsl:evaluate - Saxon - Saxonica Developer Community

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Bug #5626

closed

Incorrect inference regarding static context item type in xsl:evaluate

Added by Michael Kay over 2 years ago. Updated almost 2 years ago.

Status:

Closed

Priority:

Low

Assignee:

Michael Kay

Category:

Internals

Sprint/Milestone:

Start date:

2022-07-29

Due date:

% Done:

Estimated time:

Legacy ID:

Applies to branch:

11, trunk

Fix Committed on Branch:

11, trunk

Fixed in Maintenance Release:

12.0, 11.5

Platforms:

.NET, Java

Description

The static type checking for the expression evaluated using xsl:evaluate assumes that the context item type will be the same as the context item type for the xsl:evaluate instruction itself.

I haven't found any adverse consequences on the 11.x branch, but it's causing a crash on 12.x because we aren't checking for the context item being absent in test evaluate-024.

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Updated by Michael Kay over 2 years ago

Category set to Internals
Status changed from New to Resolved
Applies to branch 11, trunk added
Fix Committed on Branch 11, trunk added
Platforms .NET, Java added

I haven't been able to devise a test case that demonstrates the problem in Saxon 11.

The only thing we are getting wrong is the inference of whether the context item may or may not be absent, and I think we only use that knowledge when we are generating bytecode (it means we can avoid generating a run-time check for the condition). But we never generate bytecode for the expression evaluated using xsl:evaluate, so the fact that our inference is wrong has no impact.

Nevertheless, I will apply the correction.

For the 12.x branch I've changed the xsl:evaluate code to set the inferred context item static type more precisely, by looking at what can be inferred from the supplied context-item expression.

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